1. Field of the Invention
The present invention relates to organic luminescent materials for EL (electroluminescent) devices and to EL devices, and more particularly it relates to organic luminescent materials for EL devices which exhibit electroluminescence upon the application of a voltage, and to EL devices which employ the above-mentioned organic luminescent materials for EL devices.
2. Description of the Related Art
EL devices employing luminescent materials which exhibit electroluminescence upon the application of a voltage are conventionally used in backlights for displays of OA machines such as word processors and for automobile meters and the like.
Although inorganic luminescent materials have conventionally been used as the luminescent materials for such EL devices, high driving voltages have been required when inorganic luminescent materials for EL devices are caused to emit high-intensity light.
Recently, therefore, research has been conducted in regard to organic luminescent materials for EL devices which allow lower driving voltages (see, for example, C. W. Tang and S. A. VanSlyke: Appl. Phys. Lett. 51. 913 (1987)).
Thin-film EL devices employing such organic luminescent materials make it possible to use lower driving voltages than with EL devices which employ the conventional inorganic luminescent materials for EL devices.
There have also been reported organic luminescent materials which exhibit blue luminescence, and which may be suitably used in backlights for OA machine displays and for automobile meters and the like (see, for example, Jpn. J. Appl. Phys. Vol. 32 (1993) L511).
However, because of the inadequate luminescent intensity of conventional organic luminescent materials exhibiting blue luminescence, organic luminescent materials for EL devices and EL devices have been sought which are capable of blue luminescence of ever higher intensities.